1. Field of the Invention
The present invention relates generally to surfactants that include a dielectric sludge, and more specifically to such surfactants which are prepared for use with carbonaceous materials including oil and coal.
2. Discussion of the Related Art
Many industries throughout the world are at least partially dependent on the use of carbonaceous materials as fuels. Among the different carbonaceous materials, crude oil and coal are the most common. However, crude oil and coal are difficult to access. In addition, processing of these materials includes removal of impurities by methods that are usually expensive and cumbersome to perform.
Crude oil exists in subterranean reservoirs throughout the world, and, prior to use, this material must first be removed from the reservoirs. Typically, the crude oil is removed through wells which are drilled into the reservoirs. The oil is extracted from the subterranean reservoirs by pumping, but, due to the relatively high viscosity of crude oil, such pumping is difficult.
Existing methods for reducing the viscosity of crude oil predominantly include the of solvents and/or crude oil at elevated temperature. However, as the temperature of the mixture decreases, the crude oil becomes thicker, making it more difficult for subsequent transportation such as through pipelines. Therefore, these methods often utilize heating stations to maintain the elevated temperature of the mixture, but, even with the use of such heating stations, a residual may be left which eventually leads to blockage of the pipeline. Hence, these methods are relatively expensive and can be ineffective.
Surfactants have also been used to reduce the viscosity of crude oil, but the Surfactants used in currently available methods are generally expensive and difficult to produce.
Subsequent to its extraction from the subterranean reservoirs and prior to its purification, the crude oil may be stored in tanks for several days. During this time, sludge may settle at the bottom of these tanks and remain there after the crude oil is removed. As a result, the tanks should be cleaned to remove the sludge. However, this process can be time consuming and expensive.
Purifying crude oil usually includes removing impurities and separating the various constituents of the crude oil. Typically, both impurity removal and crude oil separation are performed by distillation or refining processes which are well known in the art, but crude oil often contains certain compounds, such as sulfurous compounds, that are not removed by distillation or refinement. It is desirable to remove these sulfur containing compounds from crude oil because they have a broad range of utility in various processes such as organic synthesis.
U.S. Pat. No. 3,617,529 discloses a method for removing elemental sulfur contaminants from petroleum oils containing less than 1-1.5% elemental sulfur. This reference discloses that sulfur may be removed from the oil prior to refinement by mixing the oil with an aqueous solution containing sodium hydrosulfide or a mixture of sodium hydrosulfide and sodium hydroxide and/or ammonium hydroxide. Once the reaction is complete, the aqueous phase is separated from the oil and the sulfur is purified from the aqueous phase. However, while this method has some degree of success, it is comparatively expensive to carry out on an industrial scale.
Other methods of removing sulfur-containing impurities from crude oil include reacting the crude oil with sulfuric acid or alkali. In addition, absorption techniques are commonly used to remove impurities. Moreover, catalytic methods have been used to purify crude oil, but these techniques have limited success and can be rather expensive.
Coal is another carbonaceous material that is commonly used as a fuel. In addition, coal is often modified to form coke, a coal by-product, which is used as a reducing agent in the iron and steel industries.
The chemical composition, and therefore quality, of coal varies widely depending upon the location of the coal deposit. In general, high quality coal has a relatively low percentage of impurities and is relatively easy to process. However, high quality coal is usually located relatively deep within the earth so that accessing the coal is comparatively difficult. In contrast, lower quality coal is located relatively close to the earth's surface, making it easier to access. However, this coal is difficult to process due to its relatively high percentage of impurities. Thus, there exists a trade-off between the cost of accessing coal and the cost of processing coal, and, in many cases, it is preferable to use lower quality coal due to its much lower accessing costs.
One problem with using low quality coal is that sulfur compounds and nitrogen compounds are common impurities. Upon combustion, both SO.sub.x and NO.sub.x materials are produced and these materials create pollution that is believed to result in acid rain. Furthermore, various carbon containing gases that may cause the greenhouse effect are produced. Hence, there has been an active effort to lower the amount of these pollutants produced by the combustion of coal.
U.S. Pat. No. 4,936,037 discloses a method for enhancing sulfur capture during combustion or gasification of coal. The method includes mixing the coal with a sulfur absorbent prior to exposing the coal to high temperature. The sulfur absorbent used includes calcium oxide, calcium hydroxide, calcium carbonate, limestone, dolomite or a mixture of these materials. However, while this method can be effective in removing sulfur from coal, the sulfur is not recovered in the form of a readily usable material.
U.S. Pat. No. 5,240,592 discloses a short residence time, hydrodisproportionation process that utilizes thermohydrocracking to produce hydrocarbon products without producing sulfur or nitrogen containing gases. While this method is highly effective in reducing SO.sub.x and NO.sub.x compounds, the method is expensive and cannot be used for producing a coke product sufficient for use in the iron or steel industry.
Systems used in coking industries within industrialized nations, such as the United States, are sophisticated and fairly effective in reducing pollution, but they are also very expensive. As a result, they are not used in many non-industrialized nations, including many South American countries.
A typical coking "factory" in South America consists of a grouping of several furnaces in close proximity to the coal mines. Generally, these furnaces have only chimneys, filters or hives to reduce environmental contamination. As a result, the rate of pollution is increasing dramatically within these countries. Therefore, it is desirable to provide a method of purifying the gaseous by-products of coal combustion to reduce or eliminate the amount of sulfur and nitrogen containing compounds produced.
Therefore, it remains a challenge in the art to provide a material or method that is capable of increasing the efficiency of crude oil processing while maintaining a relatively low cost. It also remains a challenge in the art to develop a comparatively inexpensive material or method that can reduce pollution from coal combustion.